Silylcarbonylation, also called silylformylation, of acetylenes (alkynes) has been studied extensively, due to its potential for forming reaction products that are useful in synthesizing novel organic molecules and pharmaceutical intermediates. For example, I. Matsuda et al, J. Amer, Chem. Soc., Vol. 111, 2332 (1989) report the silylcarbonylation of alkynes with carbon monoxide and a silane using a catalyst such as Rh.sub.4 (CO).sub.12. When the silane is a trialkylsilane, the product generally formed by way of the Matsuda et al process is in both isomeric forms, the Z-and the E-forms, and with little regioselectivity of addition. In order to get regioselectivity of addition, phenyldimethylsilane is used.
I. Ojima et al, Organometallics, Vol. 10, 38 (1991) report a similar reaction catalyzed by Rh-Co mixed metal carbonyl clusters. Depending on the nature of the silane used, the product is reported to be either a silylcarbonylated product only or a mixture of silylcarbonylated and hydrosilylated products. Trialkylsilanes generally gave a mixture of both, while phenyldimethylsilane gave the silylcarbonylated product exclusively with regioselectivity of additiG6 on and in the Z-form.
Due to the commercial significance of silylcarbonylated products, there is a continuing interest in identifying improved methods to prepare such compounds from low cost starting materials which is an object of the present invention.
It is a further object of the present invention to have such reactions yield the silylcarbonylated product, without substantial contamination by hydrosilylated product.
It is another object of this invention to form a silylcarbonylated product from alkynes substantially as one isomer (the Z- or the E- isomer) and with regioselectivity of addition, by a catalytic process wherein the catalyst enables the applicability of a wide range of silanes.